Mowing machines for golf course fairways, athletic fields and similar applications require high precision cutting. The machines may include a vehicle frame supported by front and rear wheels, an operator station, and three, five or more cutting units. Each cutting unit may cut blades of grass between a reel rotating on a shaft with a horizontal axis, and a bed knife. Each cutting unit may be supported by a lift arm extending from the vehicle frame, and a coupling mechanism attaching the cutting unit to the lift arm.
Coupling mechanisms must allow the cutting unit to traverse and cut grass on humps, slopes and other irregular surfaces without damaging the surfaces. To accommodate ground surface variations, the lift arm supporting the cutting unit may apply a downforce to the cutting unit, and the coupling mechanism may allow the cutting unit to pivot sufficiently on a horizontal axis so that the cutting unit may pivot or float over the grass surface.
Additionally, coupling mechanisms should allow cutting units to pivot or steer on a vertical axis when the vehicle turns. This helps minimize the tendency of the cutting unit to drag, scuff, or otherwise damage the turf during mowing.
Coupling mechanisms also may allow cutting units to be raised using the lift arm to a transport position when driving the vehicle between different locations and/or on paved roads. Additionally, some coupling mechanisms allow raising cutting units with the lift arm to a service or maintenance position, in which reel to bed knife clearance and height of cut may be properly adjusted, and other maintenance operations also may be performed.
U.S. Pat. Nos. 5,293,729, 5,297,378, 5,343,680 and 5,459,984 assigned to Deere & Company, and U.S. Pat. No. Re. 34,921 assigned to The Toro Company, provide examples of mowing machines for golf course fairways with coupling mechanisms.
Existing coupling mechanisms for reel-type mowers on mowing machines for golf course fairways and similar applications are relatively expensive and complex, and contribute to the cost and assembly time of the mowing machine. There is a need for a lower cost, simplified coupling mechanism for attaching cutting units to mowing machines used on golf course fairways, athletic fields and similar applications.
Existing coupling mechanisms also tend to partially block the path of grass discharged from the cutting unit into a grass catcher. If the coupling mechanism disrupts flow of clippings into the grass catcher, it may cause uneven filling and blockage at the catcher opening. A coupling mechanism is needed to reduce or minimize blockage of grass discharge from a cutting unit into a grass catcher.